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IPtables

December 14th, 2011 Leave a comment Go to comments

IPtables:

 
Exact meaning of an option which are used in iptable command:


A – All source
I – INPUT
s – Source
j – jump on

Procedure:

For Example: If you want to check IP 49.248.23.83 is blocked or not then fire command


iptables -nL | grep 49.248.23.83

You can see the result as below

DROP all — 49.248.23.83 0.0.0.0/0
DROP all — 0.0.0.0/0 49.248.23.83
 
Which means IP is blocked

To unblock that IP address use following command:


iptables -I INPUT -s 49.248.23.83 -j ACCEPT
 
To Block back an IP Address:
 
iptables -A INPUT -d 49.248.23.83 -j DROP

After adding or removing ips from iptables you need to save iptable rule using following command.
service iptables save
 
service iptables restart
 
To allow PORT in iptables you have to follow below commands

Exact meaning of an options which uses in the command
=====================================
p – protocol

dport – destination port
j – jump on
=====================================

iptables -I INPUT -p tcp –dport 2082 -j ACCEPT

iptables -I INPUT -p udp –dport 2082 -j ACCEPT

iptables -I OUTPUT -p tcp –dport 2082 -j ACCEPT

iptables -I OUTPUT -p udp –dport 2082 -j ACCEPT

To drop (block) port in iptables you have to follow below commands:

iptables -I INPUT -p tcp –dport 2082 -j DROP

iptables -I INPUT -p udp –dport 2082 -j DROP

iptables -I OUTPUT -p tcp –dport 2082 -j DROP

iptables -I OUTPUT -p udp –dport 2082 -j DROP

After adding or removing iptables you need to save iptable rule using following command.

  • service iptables save
  • service iptables restart

To enable range of port in iptables

 
iptables -A INPUT -p tcp –destination-port 1568:1570 -j ACCEPT

iptables -A OUTPUT -p tcp –source-port 1568:1570 -j ACCEPT

 
  • service iptables save

  • service iptables restart

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